The objective of this project is to develop and validate a modular instrument measuring quality of life outcomes from oral health care. The need for such an instrument has emerged from oral health surveys that have demonstrated poorer quality of life among people with untreated oral disease and inadequate dental care. However, recent findings suggest that instruments used to measure oral health related quality of life (OHRQOL) in such surveys are unsuited for use in outcomes research, in part because they appear to capture aspects of OHRQOL that are unresponsive to short term change. This project aims to synthesize core questions from five existing OHRQOL instruments, then develop and evaluate the reliability and validity of the core instrument for assessing effects of oral health care. Additional aims will: examine relationships between OHRQOL and generic health related quality of life; compare psychometric and utility-based measures of OHRQOL; and determine what additional explanatory power is gained from the addition of supplementary modules to the instruments core set of questions. Secondary, analysis of data from representative populations that have used OHRQOL instruments in oral health surveys will be undertaken to synthesize a set of questions that are associated with dental care variables, and confirmatory qualitative research will be used to assess the adequacy of those questions. Comparative rating procedures will be used to obtain patient-preference weights for items in the core questionnaire and prototype supplementary modules. Test- retest and internal consistency reliability will be evaluated among 200 community members. Validity will be assessed in four quasi-experimental sub-studies of patients receiving oral health care: 51 temporomandibular disorder patients, 508 patients receiving general dental care, 126 dental implant patients, and 56 dental patients with HIV infection. Two of those sub-studies will concurrently evaluate changes in a generic quality of life measure (SF-36) and changes in utility measurements of health status, and two sub-studies will evaluate the performance of supplementary modules of OHRQOL.